Roofs of air-supported fabric panel construction, for example of the type disclosed in U.S. Pat. Nos. 3,772,836, Geiger, and 3,835,599, Geiger, have been constructed on large structures such as athletic stadiums and field houses as these roofs provide an unobstructed interior of large size. As is discussed in pending U.S. patent application Ser. No. 624,759, filed June 26, 1984, entitled SAFETY RIGGING SYSTEM FOR INFLATABLE ROOF STRUCTURES (the disclosure of which is hereby incorporated by reference), snow accumulation on such roofs can lead to excessive loading of the structure and the partial or total collapse thereof. The above identified application discloses a rigging system which permits workers to move safely across the roof surface to conduct snow removal operations, for example.
It will be appreciated that, on a domed roof structure, the outboard regions of the roof, those adjacent the vertical walls of the structure, are normally subjected to the greatest accumulation of snow as the aerodynamic configuration of the roof results in increased snow deposition in these regions and the fact that the snow removal processes on the remaining portions of the roof moves the snow toward the periphery. In addition, due to the curvature of the roof, these regions have the greatest slope. Consequently, the outboard regions of the roof represent the most hazardous zones for workers on the roof. Moreover, a snow removal crew always must traverse the outboard regions in order to reach other portions of the roof.
In light of the increased hazards encountered at the periphery of the roof, additional safety provisions in these regions are desireable. The ability to rapidly recover a worker who has fallen through an opening in the roof without requiring others to be on the roof is obviously an advantage, particularly as the occurance of an opening in a roof panel results in a dangerous working condition on both the damaged panel and the adjacent panels.
It is the primary object of the present invention to provide a rigging system for use on inflated roof structures which facilitates the recovery of the worker in the event of the collapsing or tearing of the roof panel.
It is a further object of the present invention to provide a safety rigging system for use on an inflated roof structure which permits the recovery of a worker following the failure of a roof panel without requiring others to climb upon or move on the roof structure.
It is also an object of the present invention to provide such a rigging system which may be incorporated into the structure of an air-supported fabric panel roof structure at the time of construction or installed on an existing roof of that type with a minimum of modification thereof.
Another object of the present invention is the provision a safety rigging system for use on air-supported fabric panel roof structures which allows the worker a substantial freedom of movement under normal working conditions.